xxii INTRODUCTION 



cotton, corn, and oats and cowpeas. The first of these is a four- 

 year rotation which should include a catch crop of clover seeded 

 the first year and plowed under for corn as late as practicable in 

 the spring of the second year. The other two are three-year 

 rotations, and they should also include legume catch crops wherever 

 practicable. In each rotation for grain farming, all products are 

 to be returned to the soil excepting the grain, or seed, and the cotton 

 lint. Either the whole cotton seed or the hulls and meal should 

 also be returned for fertilizer. 



(15) In live-stock farming the feeding should be done on the 

 fields so far as practicable, and manure produced in the barn should 

 be hauled and spread in the fresh condition so far as possible. 

 Sufficient bedding should be used to absorb all of the liquid excre- 

 ment, which is as valuable, ton for ton, as the solid excrement. 



(16) To insure the maintenance of the phosphorus content of 

 the soil where large crops are produced, about 20 pounds of phos- 

 phorus per acre for each year in the rotation should be applied in 

 grain farming and about 10 pounds per acre in live-stock farming 

 (aside from that returned in the manure). To enrich the soil in 

 phosphorus, heavier applications should be made for a time. 



(17) The average investment required for 25 pounds of phos- 

 phorus is about 75 cents in 200 pounds of fine-ground natural 

 rock phosphate of good grade, about $2.50 in 200 pounds of good 

 steamed bone meal, about $3.00 in 400 pounds of good acid phos- 

 phate, about $6.00 in 600 pounds of the average " complete " 

 commercial fertilizer, and about $80 in manure made from corn 

 costing 40 cents a bushel. The natural phosphate, if ground to 

 pass through a sieve with 10,000 meshes to the square inch, gives 

 satisfactory results when applied in liberal amounts (as 1000 pounds 

 per acre every three or four years), if used in connection with 

 decaying organic matter in sufficient amount to maintain the 

 nitrogen. 



(18) Potassium salts are used with very great profit on soils 

 positively deficient in that element, as on most well-drained ex- 

 tensive peaty swamp lands; and soluble salts, such as kainit, 

 may produce some profit for a time if used in connection with 

 phosphorus on soils deficient in decaying organic matter, even 

 where the total supply of potassium in the soil is very large. 



